1. Field of the Invention
The present invention relates generally to the field of electronic length measuring devices and more specifically, to an apparatus for measuring the distance between two remote points, such as remote ends of a transverse wall in a room interior for determining the length of such a wall.
2. Background Art
The conventional method for determining the length of an interior wall is to simply use a tape measure or the like extended the full length of the wall or to simply xe2x80x9cwalk offxe2x80x9d the distance between the ends of the wall. Using a tape measure is often inconvenient for one individual. Moreover, obstructions such as furniture may prevent convenient placement of the tape measure adjacent or on the wall to be measured. xe2x80x9cWalking offxe2x80x9d the length of a wall is inherently inaccurate and can also be rendered inconvenient by obstructions adjacent the wall.
Measurement of wall length is a common requirement for real estate agents, carpenters, carpet layers, painters, architects, interior decorators, builders and others who need to know interior wall dimensions in their respective professions. It would be highly advantageous if there were an apparatus for measuring wall length electronically which would obviate the more conventional and less convenient techniques of manual measurement. Solid state lasers have made length measurement far more convenient and practical. By way of example, U.S. Pat. No. 5,652,651 to Dunne discloses a laser range finder for use on a golf course for measuring distances up to 1,000 yards with an accuracy of xc2x11 yard. Scaling such an apparatus for measuring interior room dimensions of less than 100 feet with an accuracy of xc2x10.1 feet, would be a simple matter of altering timing devices and pulse widths. Repeating the measurement many times and employing statistical averaging could increase the accuracy to within a fraction of an inch. Unfortunately, even such an electronic distance measuring device would present certain inconveniences. For example, the device would have to be positioned at one end of the wall to be measured and pointed at the opposite end. Moreover, with an accuracy of less than one inch, the device""s length would have to be calculated into the length measurement and the position of the device in relation to one end of the wall would be critical. Furthermore, obstructions adjacent or on the wall (i.e., wall hangings) would interfere with the measurement process. It would be far more convenient if such measurement of the length of an interior wall could be accomplished using an electronic length measuring device that is located some distance from the wall during the measurement.
A search of the prior art patents shows that there are disclosures of devices for making interior measurements from a position separated from interior walls. By way of example, U.S. Pat. No. 5,091,869 discloses a computer integrated floor plan system and U.S. Pat. No. 6,006,021 discloses a device for mapping dwellings and other structures in three-dimension. However, both of these prior art patents disclose extremely complex systems requiring G.P.S., radar and/or complicated computer programs. None of such prior art discloses a simple, small, handheld, portable device which can be located in a room interior to simply and conveniently measure the length of a transverse wall in a matter of seconds so that measurements of numerous interior wall lengths can be accomplished within a few minutes. Clearly, a need still exists for such a device.
The present invention meets the aforementioned need in all respects. A preferred embodiment comprises a simple-to-operate, small, portable, handheld apparatus that is positioned at a location remote from a wall, the length of which is to be measured. The preferred embodiment is implemented using two laser-based pointer devices connected on a common housing through a shaft encoder. Each pointer device has a laser transmitter and detector for determining the distance to selected points at opposite ends of a wall. The angle between the pointers is determined by a shaft encoder as one of the two pointers is rotated from pointing at a first edge of the wall to the point at the second edge while the other of the pointers remains directed toward the first edge. The respective distances to the first and second edges are measured simultaneously. These respective distances and the angle between the pointers provide sufficient data to permit a microprocessor to calculate the distance between the wall edges, thus the length of the wall. Of course, it will be understood that the pointer targets can be selected to measure length in any direction, i.e., horizontally, vertically, diagonally, et cetera. Thus, for example, the same apparatus may be used to measure the height of a wall between a floor and a ceiling or the length of a floor or ceiling between two vertical walls.
In a second embodiment of the invention, only one laser-based pointer device is required. The pointer is first used to determine the distance to one edge of the wall or other surface and is subsequently used to determine the distance to another edge of the wall or other surface. This second embodiment preferably comprises a reference base such as a suction bell which stabilizes the device on an underlying surface (i.e., floor) so that rotation of the single pointer may be accomplished accurately between the two distance measurements. A shaft encoder again provides a measurement of the angle through which the pointer is rotated. The second embodiment is also provided with an articulatable member to orient the axis of the shaft encoder in any desired direction while the reference base remains fixed on the underlying surface.
A third embodiment of the invention is a hybrid of the first two embodiments. This embodiment also uses two pointer devices as in the first embodiment. However, one such pointer device has no receiver function and acts only to pinpoint a location on a remote edge of the wall to be measured. The second pointer device, which does have a receiver, is used to measure both distances. First the two pointer devices are aligned and the corresponding distance measured. Then the moveable pointer (with the receiver) is rotated while keeping the fixed pointer device directed at the first measuring point. The included angle and second point distance are then measured. This embodiment thus employs the two pointer devices of the first embodiment, but by making the measurement in a two-step sequential process, one pointer need not provide a receiving function.
It is therefore a principal object of the present invention to provide an electronic wall length measuring apparatus which is used at a distance from the wall to be measured.
It is another object of the invention to provide an electronic length measuring apparatus implemented in a handheld, portable configuration which is held at a location remote from a surface, the length of which is to be measured.
It is still another object of the invention to provide a length measuring apparatus which calculates length of a transverse wall by electronically measuring the distances to opposing edges of the wall and the angle between the paths corresponding to such distances.
It is yet another object of the invention to provide a method for measuring the distance between two remote points by measuring the distance to each such point and the included angle and then calculating the distance between the two points.